Despite the rapid development of computer technology, network security is still a critical issue. One of the most common are XSS vulnerabilities that allow an attacker to gain complete control over an Internet resource. To ensure that your site is secure, you should scan it for this vulnerability.
Instructions
Step 1
The essence of the XSS vulnerability is the ability to execute a third-party script on the server that allows a hacker to steal confidential data. Usually, cookies are stolen: by substituting them for their own, an attacker can enter the site with the rights of the person whose data he stole. If this is an administrator, then the hacker will also enter the site with administrator privileges.
Step 2
XSS vulnerabilities are divided into passive and active. The use of passive assumes that the script can be executed on the site, but not saved on it. To exploit such a vulnerability, a hacker must, under one pretext or another, force you to click on the link sent by him. For example, you are a site administrator, receive a private message and follow the link specified in it. In this case, the cookies go to a sniffer - a program for intercepting the data the hacker needs.
Step 3
Active XSS are much less common, but much more dangerous. In this case, the malicious script is saved on a website page - for example, in a forum or guestbook post. If you are registered on the forum and open such a page, your cookies are automatically sent to the hacker. That is why it is so important to be able to check your site for the presence of these vulnerabilities.
Step 4
To search for passive XSS, the string "> alert () is usually used, which is entered in the text input fields, most often in the search field of the site. The whole trick is in the first quote: if there is an error in filtering characters, the quote is perceived as closing the search query, and the script after it is executed If there is a vulnerability, you will see a pop-up window on the screen. Vulnerability of this type is very common.
Step 5
Finding active XSS begins by checking which tags are allowed on the site. For a hacker, the most important are the img and url tags. For example, try to insert a link to a picture in the message like this:
Step 6
If the cross appears again, the hacker is halfway to success. Now it adds one more parameter after the *.
Step 7
How to protect a site from attacks through XSS vulnerabilities? Try to have as few data entry fields as possible. Moreover, even radio buttons, checkboxes, etc. can become "fields". There are special hacker utilities that display all hidden fields on the browser page. For example IE_XSS_Kit for Internet Explorer. Find this utility, install it - it will be added to the browser context menu. After that, check all the fields of your site for possible vulnerabilities.
